This application is based on applications Nos. 293710/1997, 293711/1997 and 297182/1997 filed in Japan, the contents of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an image forming apparatus so adapted that an electrostatic latent image is formed on the surface of an image carrying member, a non-conductive release agent is applied to the surface of the image carrying member, and ink in an ink developing device is brought into contact with the surface of the image carrying member thus having the electrostatic latent image formed thereon and the release agent applied thereto, to form an ink image corresponding to the electrostatic latent image on the surface of the image carrying member.
2. Description of the Related Art
Conventionally, an image forming apparatus so adapted that an electrostatic latent image is formed on the surface of an image carrying member, and the electrostatic latent image is developed, and is then transferred onto a recording medium such as paper, to form an image on the recording medium has been conventionally used, as represented by an electrophotographic copying machine.
Known as an example of such an image forming apparatus utilizing an electrophotographic system is one using a liquid developer obtained by dispersing colored resin particles (toner particles) in a carrier liquid in order to develop an electrostatic latent image, as disclosed in JP-A-7-271107.
The liquid developer used in the electrophotographic apparatus is generally obtained by dispersing charged toner particles in an insulating carrier liquid. The toner particles are selectively consumed from the liquid developer as an image is formed. When the liquid developer is used, therefore, the density of the toner particles in the carrier liquid must be managed. The management is troublesome. Further, a large part of the carrier liquid is repeatedly used, so that the liquid developer is liable to be degraded.
Furthermore, in the electrophotographic apparatus thus using the liquid developer, when the image is formed on a recording medium such as copying paper, a fixing device for fixing a toner image transferred onto the recording medium, for example, is required. Therefore, the apparatus becomes complicated and is increased in size.
Conventionally, an image forming apparatus so adapted that an electrostatic latent image is formed on the surface of an image carrying member, a non-conductive release agent is applied to the surface of the image carrying member, ink held in an ink carrying member in an ink developing device is brought into contact with the surface of the image carrying member thus having the electrostatic latent image formed thereon and the non-conductive release agent applied thereto, and the ink is made to adhere to a portion, where the electrostatic latent image is formed, on the surface of the image carrying member, to form an ink image corresponding to the electrostatic latent image on the surface of the image carrying member has been proposed, as disclosed in U.S. Pat. No. 4,272,599.
In a case where the ink held in the ink carrying member is brought into contact with the surface of the image carrying member thus coated with the release agent, to form the ink image in the portion, where the electrostatic latent image is formed, on the surface of the image carrying member, the release agent applied to the surface of the image carrying member is introduced into the ink developing device with a part of the release agent held in the ink carrying member, and the release agent is mixed with the ink in the ink developing device, so that the viscosity of the ink in the ink developing device is gradually changed. Consequently, the ink also adheres to a portion, where no electrostatic latent image is formed, on the surface of the image carrying member, so that a formed image is fogged, for example.
In a case where the ink held in the ink carrying member is brought into contact with the surface of the image carrying member coated with the release agent, to form the ink image in the portion, where the electrostatic latent image is formed, on the surface of the image carrying member, as described above, when environmental conditions such as temperature under which the image forming apparatus is employed are changed, the viscosity of the ink in the ink developing device is changed. Consequently, the ink does not suitably adheres to the portion, where the electrostatic latent image is formed, on the surface of the image carrying member, so that the density of a formed image is decreased. Further, the ink also adheres to the portion, where no electrostatic latent image is formed, on the surface of the image carrying member, so that the formed image is fogged, for example.